Method for separation of gas suspended dust particles



Dec. 22, 1953 DAUTREBANDE METHOD FOR SEPARATION OF GAS-SUSPENDED DUST PARTICLES Filed Nov. 24, 1948 /J INVENTOI?.

LUCIEN DAUTREBANDE om); 23A TTORNEYS.

Patented Dec. 22, h1953 'METHOD FOR SEPARATION QLFGAS SUSPENDEDnUSTiiARTICLES Lucien Dautrebande, Washington, C. .assignor to Aerosol Corporation of1 America, NewV York, N. Y., a corporation of Delaware Y .eppiaanonirsvemherze 1.9.18, saisine etats ciaimsrriorityi application Belsiilm The present invention relates to. .method ier' eliminating dust particles in suspension .in.con\

taminated zones, and especially to particles. of.

a mean size (diameter) of not over about. 0.5

micron.

The particular methods used for `elinlinating dusts vary in accordance with the nature of the particles to be treated, such as silica, coal, nega:` table dusts, metallic dusts, and the like... 'Hows ever, a coinnion `characteristic is encountered.

when considering the retention, precipitation or elimination of particles having :a diameterxless than one or two microns.

It is known that certain dust particlesfdg not;v

have dangerous characteristics Yexcept to sensi?- tive individuals. Particles, for example., gernv erally exceeding rite microns in size,..step. in .the upper respiratory passages or in the large-brcr1--4 chi', and as they do not penetrate in to. .the depths of the lungs are easily .expelledaiter irlhalation, by vibratile bronchial cilia. Dusts smaller than two microns may penetrate into innermost passages or regions (alveoli) inthe lungs, and may, for want of meansof evacuatidn..

produce damage not only locally but. ,Siren in the. lymphatic system, the kidney., the livel', the spleen, etc. after absorption.

Moreover, in the case of duets of .one micron or under in size, practically the entire. amount. or the dust is recovered in the fine. b IQnQhiQl, the alveolar tubes, andthe alveolar sacs... it can be Shown that these very fine dusts are not expelled through the respiratory passages by systeniatically examining lungs experimentally iinpregnated therewith and observing the condition of the alyeoli'dnring the time following the experiment. Furthermore, as it is known that they extreme division of silica clusts,l for example, increases the surface of the particles with 17.- spect to their weight and in this fine condition may cause harmful action on the pulmonary tissues, it is evident that the liner the dust, the greater the danger therefrom.

heretofore. keffe-:tive method of oombattine these subinicronic particles has been used. In the existing methods, particles of relatively large size have been eliminated by means of water sprays or by extraction, such as by forcing the dust to pass through a continuous liquid layer. However, it has been found that (l) a water spray fails to remove the smallest size particles and (2) particles, of two microns or less, pass without diculty through layers of continuous and turbulent water.

It is an object ci the present invention to prokNovember 25, 194'? 4. .Qlnillii f(C1. 183711.22)

vide lnew and .improved method for eliminating dust particles suspended in contaminated lsones, especially theseA particles having la mean size et adeniiemicron. As aresult of the elimination Aci suohsdnst, a workery inthecontaminated poneisnot exposed to the inherent dangers .previmisiyv associated therewith.

; abject. asv well. as others isV attained bythequtlliationethe processidisclosed in .the ich' lowing detailed description. In accordance with thaimntdn, liquid. aerosols, .more particularly leef' .Water,..rir .water solutions ef moistenilg @gema saline salta. vandntherv suitable. mine.

QlTaLori .organic .substances are. dispersed. .inte Chiot filled zeneihyzdirecting. a current oi aerosols.v

into .auch .a .dust contaminated `miie. if the. Giusi@ .are then.. collected. .and examined under oltllor `optical...micrescent,` a microproiector or. electronic niiecroscope. it will. .te .seen that. the dust particles, even the nest, upon associa: iQll. ,the .limitent of aerosols: become coated with liquid-.sancire 'lhisand supplementary agglomeraties to .increase .the sise of the dust parti 1 condensation i. the aerosol particles. ,unonthe dust particles 'can' be .elflliarlced employing. Solutionscontainina'a soluteas a saline Salte. calcium." or Valmaislum chloe Hdaoro .er nahleinlneral or .organic .sans stancea The her the .concentration of. the solute. the, lans@ and more .numerous are the aggregates-Which re f the. aercsol isf fdispe1sed .a noi @Initiated ,zone and, there riore, it is preferred to employ strong solutions4 oo11tai1iinefrom5to-lQ-f@ oie solute @tiene Solutions-oiliiieriraleno products., i... e, salts ,ai mail loner cations. ,give particularly improved, ythe.aser,esaoion of the dust particles the oi niet@ Water alone .ihesiz i of. the. asalomeratedmasses .made un 0i" the.' dust.. particles may he. .increaseol.` to. f1.0.111....5lv to .30 microns and these .new masses, as aresurt .of the aerosol.' treatment.. .may contain from.ltaseyeraihundrediline particles.. 'lneY largercoinpose masses or agglomerates' are also coated with a liquid nlm made up of the aerosols which have been brought into contact with them.

To eiiect such elimination, the aerosols should be stable gaseous colloids whose average pai'- ticle size does not exceed 0.5 micron. The aerosols may be obtained by the apparatus described and claimed in my co-pending United States application, ISerial No. 40,947, now Patent No. 2,605,088, issued July 29, '1952. The aerosols described in the above-mentioned application are vand.lllllliiy their .lffmehnessYV The- 3 spontaneously charged electrically, and may also be charged articially to provide additional means for combatting a specific dust. The aerosols may be made of substances eective to neutralize certain irritating caustic dusts.

As the aerosols upon issuing from the generator may number several hundred thousands per cubic millimeter of air, contact is assured between the dust particles and the aerosols. Experiments have shown that under such conditions, whatever number of dust particles may be present in the atmosphere (up to 500,000 per cubic centimeter of air), no particle of dust escaped the aerosols. The number of dust particles present in the atmosphere per unit volume will determine the optimum amount of aerosols to be sprayed. Such a quantity of aerosols does not interfere with visibility in the case of aqueous solutions. Biological experiments have demonstrated that substances sprayed with aerosols are prevented from penetrating into the lungs exposed thereto, such as those working in coal mines, spinning mills and the like. It is apparent from these demonstrations that my invention may be utilized in both ceramic and cement factories, explosive plants and other mills or factories where dust problems exist. Thus, it can also be used effectively in factories where dust explosions are easily produced; i. e., flour, aluminum powder, etc.

Moreover, the presence of aerosols permits a worker to stay much longer in the dusty zone, inasmuch as the quantity of foreign particles penetrating into the lungs is decreased. Since, as previously stated, dust particles above about two microns do not penetrate into the depths of the lungs, but remain in the bronchi from where they may be expelled, it is easy to appreciate the importance of increasing the size of very ne particles.

The larger the particle of dust, the more rapid its sedimentation, and it is clear that if the size of the fine dust particles in a given dust zone can be increased, the dust content therein will be lowered. In addition, the existing control methods will be facilitated materially.

The invention may be better understood from the following detailed description, taken in conjunction with the accompanying drawings, in which: Figure 1 is a diagrammatic illustration of an apparatus suitable for carrying out the method of the invention in a mine; and, Figure 2 is an alternate embodiment of the apparatus of Figure 1.

Referring now to Figure 1, the apparatus is shown in a conventional coal mine having a Working area or tunnel I0, an air inlet H and an air outlet l2 being provided to permit circulation of air from any suitable blower means (not shown) therethrough. Adjacent the Working area I is the coal being mined at I3 and an area i4 serving to store the mined coal. An aerosol generator I5 is placed near the drilling tools (not shown) so that a current of air, flowing in the 4 direction of the arrow from air inlet Il, draws the aerosol to and through the area where the dust is produced.

Figure 2 illustrates an alternate embodiment ofthe apparatus wherein a suitable conduit It is joined to the aerosol generator I5. Conduit I6 conducts the aerosol to the desired working areas through a series of branch conduits il', which divert and distribute the aerosols over a more a select operating range. Branch conduits E'i may be removed and interchanged from the conduit IS, according to the nature of the operation.

From the foregoing it is apparent that the present invention provides an effective method for eliminating suspended dust in contaminated rL'ones, such as coal mines.

Obviously, the invention is susceptible to numerous Vchanges in form. The aerosol generator i5 may be placed at the air inlet l I in order to direct the aerosol-laden air onto the cut where the miners are working, and similarly for use in a factory, the aerosol generator i5 may be placed in a location such that the ventilation or con- Vection currents which prevail therein convey Y the aerosol to the origin of the dust. Moreover,

the chemical nature of the liquid aerosol may vary widely, for example, solutions of sodium chloride, calcium chloride, aluminum chloride, etc., may be used. Thus, the invention is not to be limited save by the appended claims.

I claim:

l. A method of eliminating Idust particles having a particle size of about one micron or less in suspension in a contaminated zone'which corny prises directing into the contaminated zone a stable aerosol formed from a water solution having a concentration of at least 5% by weight of a material selected from a group consisting of sodium, calcium and :aluminum chlorides, the aerosol having an average particle size of about 0.5 micron, sufcient at the point of generation to comprise at least several hundred thousand particles per cubic millimeter of air and sufcient to coat all the dust particles and cause agglomeration and settling thereof.

2. A method according to claim i in which the material is sodium chloride.

3. A method according to claim l in which the material is calcium chloride.

4. A method according to claim 1 in which the material is aluminum chloride.

LUCIEN DAUTREBANDE.

References, Cited in the le of this patent UNITED STATES PATENTS Great Britain Oct. -6, 1930 

